It’s most likely the temples or arms of the eyeglasses, the side pieces that extend back toward the ears and hold the frame in place. If you mean a small extra part attached to the frame, it could also be a nose pad , hinge , or temple tip depending on where it sits.

Common parts

  • Temples/arms : the long side pieces of the frame.
  • Temple tips : the ends that rest behind the ears.
  • Nose pads : the small pads that sit on the nose, usually on metal frames.
  • Hinges : the joints connecting the front of the glasses to the arms.

Best guess

If the object is “placed on the eyeglass” near the side, the most common answer is temple/arm. If it’s something clipped or added on top, then it may be an accessory or a repair part rather than a built-in frame component.

TL;DR: Most likely the temple/arm of the glasses.